A. Field of the Invention
This invention relates to an anti-lock brake device comprising wheel brakes, a hydraulic pressure control circuit for controlling the application of hydraulic brake pressure to the wheel brakes, and control means for detecting whether wheels are likely to lock from the rotational velocity characteristics of the wheels and for operating the hydraulic control circuit to reduce the hydraulic brake pressure applied to the wheel brakes when the wheels are likely to lock.
B. Background Information
The conventional anti-lock brake device may cause oscillation of the vehicle suspension in the longitudinal direction and pulsations in the vehicle velocity in proportion thereto if it is applied to provide braking while the vehicle is traveling on a rough road. This is because the braking force applied to the wheels changes as the ground contact of the wheels varies, even though hydraulic pressure is constant. If such pulsations are generated, the control means may mistakenly judge that the wheels are likely to lock even when they are unlikely to do so, and operate the hydraulic pressure control circuit to reduce the hydraulic pressure, thus reducing braking effectiveness and increasing the braking distance.